Chicago Fire Department crews responded Tuesday afternoon to a 2-11 alarm fire on the roof of the Blommer Chocolate Company factory in the city's Fulton River District neighborhood.

The fire was struck at about 3:30 p.m. and no one was injured, fire officials said. It is the second fire at the chocolate factory in just 11 days.

Firefighters were called to the building at about 1:45 p.m. after receiving reports of a fire burning on the roof. Flames and smoke were visible from the area around a smokestack and catwalk on the top of the building.

Employees inside the factory said alarms went off and firefighters took over to put out the fire and then determine the cause.

"At this time we think it was a mechanical fire, we're not sure. This building is full of mechanical machines for roasting cocoa and making chocolate," said Tim Walsh, chief of safety for the Chicago Fire Department.

"The fire alarm went off, everyone evacuated the building. We do take a roster of everyone that was in the building as well as all the visitors in the building, and we physically check heads to make sure everyone is out of the building," said Margaret Sophio, Blommer Chocolate Company.

The fire was contained to equipment at the factory and not in the building, the fire department said.

Calm but very active scene outside Blommer's Chocolate Factory as CFD responds to roof-top fire. Firefighters have begun exiting the building more than an hour after the call came in. pic.twitter.com/UH7D81EWvZ